1. Field of the Invention:
The present invention relates to a machine tool, and more particularly to a horizontal machining center.
2. Description of the Prior Art:
Horizontal machining centers having a horizontal tool spindle include a work table with a rotary table mounted thereon. Once a workpiece is clamped on the rotary table, four sides of the workpiece can be machined by indexing the rotary table, with the abutment side and upper side of the workpiece being not machinable. The upper side of the workpiece, however, can be rendered machinable by a vertical head fixed to the distal end of the spindle head. The conventional vertical head requires that tools for use only on the vertical head be prepared since tools used on the horizontal tool spindle cannot be automatically changed with respect to the vertical head. The vertical spindle is therefore poor in its versatility as it is limited to certain machining operations. No tools can be shared by the vertical and horizontal tool spindles.
One known type of machining center capable of machining five sides of a workpiece has a vertical spindle and a horizontal spindle both mounted on a spindle head, and also has a tool changer which is particularly designed for changing tools on the vertical and horizontal tool spindles. In another known machining center, a tool spindle is supported on a spindle head for horizontal and vertical tilt movement, and tools can be changed on the spindle when the same is placed in a horizontal position. These constructions demand redesign of the entire arrangements of machine, tool changer, and other related mechanisms. It has therefore been impossible to give the above functions to existing machine tools.